This invention relates to apparatus for producing high frequency output signals. More particularly, it is concerned with solid state high frequency power sources which employ an oscillator driving a power amplifier.
Conventional solid state high frequency power sources typically employ a low power oscillator which drives a single or multiple stage high gain amplifier. To supply dc operating power to the amplifier and the oscillator the apparatus either employs two power supplies or a single power supply having two separate power distribution networks.
One type of amplifying device which provides high gain at very high microwave frequencies is the static induction transistor (SIT), a particular type of junction field effect transistor. To obtain relatively high efficiency operation, it is necessary that SIT's be operated in class B or class C conditions. In order to provide appropriate bias between the electrodes of an SIT for class B or class C operation, it is necessary either to employ a separate voltage source or a self-biasing network which adds to circuit complexity and also reduces overall efficiency.